In general, an output driver circuit of a semiconductor memory device is used when outputting internal data to the outside through an output terminal or a DQ pad. The output driver circuit receives the internal data and drives an output data outputted to the DQ pad with a set driving strength.
FIG. 1 is a block diagram illustrating a configuration of a conventional output driver circuit.
As shown, the conventional output driver circuit includes a predriver 10 which receives an internal data DATA and generates a pull-up driving signal PUB and a pull-down driving signal PD in response to a pull-up control signal PO and a pull-down control signal NOB, and a driver 12 which receives the pull-up driving signal PUB and the pull-down driving signal PD and drives an output data DQ outputted to a DQ pad 14. The driver 12 includes a pull-up device which pulls up the output data DQ in response to the pull-up driving signal PUB and a pull-down device which pulls down the output data DQ in response to the pull-down driving signal PD.
In order to enhance an operation speed of the output driver circuit configured as described above, it is required to increase sizes of the pull-up device and the pull-down device included in the driver 12 to increase the driving strength. When the sizes of the pull-up device and the pull-down device included in the driver 12 are increased, levels of the pull-up driving signal PUB and the pull-down driving signal PD also should be increased and this also requires increase in a size of the predriver 10. The increase in the size of the predriver 10 leads to increase in current consumption upon read or write operation and reduction in the operation speed of the output driver circuit.